Conventional spindle-nut systems in conjunction with rotating motors have partly been used until now in machine tools. In the last decade, the interest in the integration of so-called numerically controlled (NC) linear motors in machine tools has grown and there are a number of machines which use such linear motors. Linear motors allow describing a translatory motion directly, which is why they are also known as direct drives. There are also direct drives which produce a rotational motion.
The demands for speed and low cost at high precision and reliability that have been rising continuously for many years have established the increased application of linear motors generally in production and automation systems and robots. Production and automation systems as well as robots shall be subsumed herein under the term “machine” for the sake of simplicity.
There are also other types of numerically controlled (NC) actuators which are used in machines. The mentioned linear motors and actuators are all controlled by a numerical control. The control either feeds in electric currents or volume flows of fluids (hydraulic fluid) are pumped into the actuator.
The common aspect in all these systems is that the moved masses of the NC axes thus driven lead to an oscillatory system with the bearings of the linear motors or actuators and the fixed parts of the machine. Depending on the operating state, oscillations will occur in such systems. These oscillations are rather undesirable however and there are various developments whose goal it has been to avoid or reduce the oscillations.
In machines that are becoming increasingly more complex and larger, it has always been desirable despite the automation to provide the user with feedback. Screens with a graphic user interface are typically used on the one hand. On the other hand, additional acoustic signal generators are often used in order to emit a warning sound prior to the start-up of a machine. The machines are equipped with respective loudspeakers and a signal source which is preferably controlled by the machine's control unit. The technical effort required for this purpose in order to make the acoustic signals audible even when the machine is running can be relatively high.
So-called start-up warning devices are partly required under law which prior to the start-up of a machine mandatorily issue a clearly audible acoustic signal.
It is therefore the object to provide a signalling system for acoustic and/or tangible signals in a machine in order to send warnings for example. The signalling system shall be as cost-effective and sturdy as possible.
It is a further object to provide a respective method which can be used in machines in order to emit signals. In this context one goal is to improve work safety.